【Kotlinプログラム入門】。ポンコツ2人組がJetpack composeでコンテンツを切り替えするプログラムに挑戦してみました！

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Surface
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import com.example.switch.ui.theme.SwipeableTheme
import androidx.compose.foundation.layout.*
import androidx.compose.material3.Button
import androidx.compose.runtime.*
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            SwipeableTheme {
                // A surface container using the 'background' color from the theme
                Surface(
                    modifier = Modifier.fillMaxSize(),
                    color = MaterialTheme.colorScheme.background
                ) {
                    ContentSwitchingExample()
                }
            }
        }
    }
}

@Composable
fun ContentSwitchingExample() {
    // Stateを使ってボタンが押されたかどうかを追跡します
    var isContentChange by remember { mutableStateOf(false) }

    // コンテンツを切り替える関数
    fun toggleContent() {
        isContentChange = !isContentChange
    }

    Column(
        modifier = Modifier
            .fillMaxSize()
            .padding(16.dp),
        verticalArrangement = Arrangement.Center,
        horizontalAlignment = Alignment.CenterHorizontally
    ) {
        // ボタンを配置します
        Button(onClick = { toggleContent() }) {
            Text(text = if (isContentChange) "Content A" else "Content B")
        }

        // コンテンツを切り替えます
        if (isContentChange) {
            Text(
                text = "Content A",
                modifier = Modifier.padding(top = 16.dp)
            )
        } else {
            Text(
                text = "Content B",
                modifier = Modifier.padding(top = 16.dp)
            )
        }
    }
}